1. Field of the Invention
The present invention relates to a vehicle body frame for a motorcycle, and to a motorcycle incorporating the same. More particularly the present invention relates to a vehicle body frame for a motorcycle which includes: a head pipe which steerably supports a front fork which pivotally supports a front wheel and a steering handlebar; a pair of left and right main frame sections which extends rearwardly and downwardly from the head pipe; a pair of downwardly extending left and right pivot plates which is joined to rear end portions of the main frame sections from the inside in a vehicle widthwise direction; and a crossmember which is arranged between upper end portions of both pivot plates and having a damper mounting portion on which an upper end portion of a damper is mounted, and to a motorcycle incorporating the same.
2. Description of the Background Art
There is a known vehicle body frame for a motorcycle, particularly, a vehicle body frame for a motorcycle suitable for all terrain traveling. An example of such vehicle body frame for a motorcycle is disclosed in the Japanese Patent Document JP-A-2006-205985. In this type of vehicle body frame, rear end portions of main frame sections are joined to upper end portions of the pivot plates, and connecting portions which are formed on both ends of a crossmember are joined to joint portions between the pivot plates and the main frame sections from inside in a vehicle widthwise direction in a way similar to how a patch is fitted.
In the vehicle body frame as disclosed in the Japanese Patent Document JP-A-2006-205985, the joint portions of the main frame sections, the pivot plate and the crossmember exhibit poor resistance against a load input in a longitudinal direction as well as against a load input in a lateral direction, and the crossmember is arranged at a relatively upper position so that an input from a damper is also relatively large. Accordingly, it is necessary to make the connecting portions, which form patches on both end portions of the crossmember, large, heavy and thick.
The present invention has been made under such circumstances. Accordingly, it is one of the objects of the present invention to provide a vehicle body frame for a motorcycle which can ensure the rigidity of connecting portions where a crossmember is connected to pivot plates without making a frame member heavy and thick.